Global Production of Marine Bivalves. Trends and Challenges

The global production of marine bivalves for human consumption is more than 15 million tonnes per year (average period 2010–2015), which is about 14% of the total marine production in the world. Most of the marine bivalve production (89%) comes from aquaculture and only 11% comes from the wild fishery. Asia, especially China, is by far the largest producer of marine bivalves, accounting for 85% of the world production and responsible for the production growth. In other continents, the production is stabilizing or decreasing (Europe) the last decades. In order to stimulate growth, sustainability (Planet, Profit, People) of the aquaculture activities is a key issue. Environmental (Planet) aspects for sustainable aquaculture include the fishery on seed resources, carrying capacity, invasive species and organic loading. Food safety issues due to environmental contaminants and biotoxines should be minimized to increase the reliability of marine bivalves as a healthy food source and to stimulate market demands. Properly designed monitoring programs are important tools to accomplish sustainable growth of marine bivalve production

Variation in Size and Growth of the Great Scallop Pecten maximus along a Latitudinal Gradient

Understanding the relationship between growth and temperature will aid in the evaluation of thermal stress and threats to ectotherms in the context of anticipated climate changes. Most Pecten maximus scallops living at high latitudes in the northern hemisphere have a larger maximum body size than individuals further south, a common pattern among many ectotherms. We investigated differences in daily shell growth among scallop populations along the Northeast Atlantic coast from Spain to Norway. This study design allowed us to address precisely whether the asymptotic size observed along a latitudinal gradient, mainly defined by a temperature gradient, results from differences in annual or daily growth rates, or a difference in the length of the growing season. We found that low annual growth rates in northern populations are not due to low daily growth values, but to the smaller number of days available each year to achieve growth compared to the south. We documented a decrease in the annual number of growth days with age regardless of latitude. However, despite initially lower annual growth performances in terms of growing season length and growth rate, differences in asymptotic size as a function of latitude resulted from persistent annual growth performances in the north and sharp declines in the south. Our measurements of daily growth rates throughout life in a long-lived ectothermic species provide new insight into spatio-temporal variations in growth dynamics and growing season length that cannot be accounted for by classical growth models that only address asymptotic size and annual growth rate

Socio-economic Aspects of Marine Bivalve Production

The aim of this book is to review and analyse the goods and services of bivalve shellfish. How they are defined, what determines the ecological functions that are the basis for the goods and services, what controversies in the use of goods and services exist, and what is needed for sustainable exploitation of bivalves from the perspective of the various stakeholders. The book is focused on the goods and services, and not on impacts of shellfish aquaculture on the benthic environment, or on threats like biotoxins; neither is it a shellfish culture handbook although it can be used in evaluating shellfish culture. The reviews and analysis are based on case studies that exemplify the concept, and show the strengths and weaknesses of the current applications. The multi-authored reviews cover ecological, economic and social aspects of bivalve goods and services. The book provides new insights for scientists, students, shellfish producers, policy advisors, nature conservationists and decision makers

Etude du phénomène de résurgence de novembre 1991 dans la passe de l'atoll d'Amanu (Tuamotu, Polynésie Française)

Un phénomène exceptionnel de résurgence d'eau a eu lieu le 3 novembre 1991 dans la passe principale de l'atoll d'Amanu (Tuamotu, Polynésie Française). Ce rapport de mission explique les causes de ce phénomène : l'érosion de la passe et l'éboulement d'un surplomb suivi de la sortie d'eaux intersticielles; ce phénomène ne présente aucun risque. (Résumé d'auteur

Assessing the production and the impact of cultivated oysters in the Thau lagoon (Mediterranee, France) with a population dynamics model

The Thau lagoon (France) has been studied for many years because of its ecological interest related to economic activities: shellfish cultivation, tourism, and industry. The standing stock of cultivated filter feeders is around 20 000 t and consists of two main species, the Japanese oyster Crassostrea gigas and the Mediterranean mussel Mytilus galloprovincialis. To predict changes in the standing stock and the annual production, a mathematical model of the population dynamics was defined. It was based on the continuous equation of the density as a function of the mortality rate, the individual growth rate, and the interindividual variability. The daily growth rate was derived from field surveys and depended on the phytoplankton concentration and individual weight. The model also took into account the rearing strategy of the producers defined by the timetable of seeding and harvesting, obtained by an inquiry among the producers and used to simulate real cases of standing stock changes. The model was also used to assess the potential impact on the environment through the computation of the food consumption, which was compared with the residence time and the primary production. </jats:p